1. Field of the Invention
The present invention relates to a method and an apparatus for transmitting a data packet of a multimedia service. More particularly, the present invention relates to a method and an apparatus for guaranteeing transmission of a data packet and a service quality by using media characteristics for a multimedia service including one or more media content components.
2. Description of the Related Art
A multimedia service refers to a conversational service such as a video telephony service, a streaming service such as a Video On Demand (VOD) service, and a multicast and a broadcast service. A real time multimedia service may be a conversational service, an interactive service, and a streaming service according to a service type. The real time multimedia service may be divided into a unicast service, the multicast service, and the broadcast service according to a number of participants in a service.
IEEE 802.16 Worldwide Interoperability for Microwave Access (WiMAX), IEEE 802.11e Wireless Fidelity Transmission Opportunity (WiFi TXOP), 3GPP Universal Mobile Telecommunications System (UMTS), and 3GPP Long Term Evolution (LTE) each have functions for reserving resources for the multimedia service and guaranteeing the reserved resources.
In traffic specification (tspec), request specification (rspec), and flow specification (flowspec) of the Resource Reservation Protocol (RSVP) of the Internet Engineering Task Force (IETF), parameters used for the resource reservation protocol are defined. The parameters are compatible with IEEE 802.16, IEEE 802.11e, 3GPP UMTS UMTS, and 3GPP LTE communication system. Resources are reserved through a double leaky bucket parameter in IEEE 802.16, IEEE 802.11e, 3GPP UMTS UMTS, and 3GPP LTE communication system.
FIG. 1 illustrates a process of expressing data of a variable bitrate by using double leaky bucket parameters according to the related art.
Referring to FIG. 1, traffic of a Variable BitRate (VBR) is indicated by the double leaky bucket by using four parameters (Rg, Rp, Bp, and B) included in tspec of RSVP.
The Rg 101, which is a guaranteed bitrate, refers to a given average bitrate. Even when a bitrate of data temporarily exceeds the guaranteed bitrate Rg 101, it is possible to prevent occurrence of overflow by storing the data in a buffer. A required buffer size is prearranged as B 103. According to circumstances, the buffer size B 103 corresponding to the guaranteed bitrate may be indicated as Bg, which is a guaranteed buffer size. A peak bitrate Rp 105 may also be prearranged. Based on an assumption that the peak bitrate Rp 105 is retained within a cycle on which one packet is transferred, a buffer size Bp 107 for the peak bitrate may be determined as a maximum size of a Service Data Unit (SDU). In general, a value of the maximum size of the SDU may be indicated in a Maximum Transfer Unit (MTU).
Table 1 below shows examples of various protocols using the four parameters of the double leaky bucket.
TABLE 1IETF RSVP,IEEE802.163GPP UMTSIEEE802.11e‘tspec’(WIMAX)& LTEMPEG-4 ODATMRppMin. reservedMaximumavgBitratePCRtraffic ratebitrate (4B)BpMSDU sizeMaximumMAX_AU_SIZECDVTSDU sizeRgrMax. sustainedGuaranteedAverageBitRateSCRtraffic ratebitrate (4B)BgbMaximumk*MaximumbufferSizeDBBTLatencySDU
Accordingly, for compatibility with a resource reservation protocol of a lower layer, the media characteristics should be configured in a form of parameters of the double leaky bucket in a multimedia content such as an MPEG (Moving Picture Experts Group) content.